1. Field of Invention
The invention relates to a method of noise value control by controlling the rotation rate of a fan and, in particular, to a method that estimates the noise value of a fan by setting a temperature control plot.
2. Related Art
Since the creation of Pentium processors, the working frequency of CPUs has ranged from 133 MHz to 2.5 GHz. Popular CPUs used the manufacturing technology of 0.18 micrometers or 0.13 micrometers, but CPUs with high-speed data processing that consist of many transistors generate more thermal energy than before. Today, the power of CPUs with a frequency up to 1 GHz is more than 40 watts, and the power of CPUs such as Pentium 4s with a frequency up to 2 GHz is 70 watts. Such high power causes more thermal energy in the CPUs. If no methods are employed for removing thermal energy immediately in summer, the CPUs may become damaged and prematurely aged. It is thus important to create fans that remove the thermal energy of computers effectively.
The thermal energy of CPUs increases rapidly with the improving working frequency of CPUs. Many manufacturers are trying methods to enhance the rotation rate of fans or include more fans for improving the removing effect. A higher fan rotation rate and more fans cause more noise. Thus finding a balance between rotation rate of fans and noise of fans is a goal of fan design.
Generally speaking, the methods of reducing fan noise can be categorized into two types: one is improving bearings of fans, and the other is reducing the rotation rate of fans. In the former method, the bearings of fans are categorized into three types: sleeve bearing fans, ball bearing fans, and magnetic bearing fans. The operation of sleeve bearing fans causes sliding friction and the operation of ball bearing fans causes rolling friction, so more noise is produced in operation. The operation of magnetic bearing fans reduces the noise of sleeve bearing friction. Acceptance of magnetic bearing fans is not as widespread because of immature manufacturing technology and high expense.
The latter method of reducing rotation rate is an obvious way for reducing fan noise. Fans of fixed rotation rates produce fixed noise values, so changing one fan to another fan is the only way to reduce the noise value. There are no definite adjusting methods for setting control parameters of rotation rate. The only method is adjusting fan rotation rate slowly until the noise value is acceptable, but this wastes manpower and time. It is thus an important issue to reduce noise value by controlling the rotation rate of a fan.
The object of the invention is to provide a method of noise value control by controlling the rotation rate of a fan. The method involves estimating the noise value of a fan by setting a temperature control plot. The method also estimates the noise value of fans and temperature changes of CPUs corresponding to the fans to optimize thermal energy absorption, achieve a suitable noise value, and take less manpower and time.
In accordance with the invention, the method of noise value control by controlling the rotation rate of a fan comprises the following steps:
acquiring a fan module first;
acquiring a corresponding relation of values of the temperature of a target member and values of the operation parameters of the fan module, and a corresponding relation of values of the operation parameters of the fan module and values of the noise;
plotting a relation chart according to values of the temperature of the target member and values of the operation parameters of the fan module, and a relation chart according to the values of the operation parameters of the fan module and values of the noise;
setting a temperature control plot, and plotting it into the relation chart according to the values of the temperature of the target member and values of the operation parameters of the fan module;
obtaining an intersection point (called an operation point) of the fan module, the temperature control plot and the relation chart according to the values of the temperature of the target member and the values of the operation parameters of the fan module;
obtaining the operation parameter value corresponding to the operation point from the relation chart according to the values of the temperature of the target member and the values of the operation parameters of the fan module;
obtaining the noise value corresponding to the operation point from the relation chart according to the values of the operation parameters of the fan module and the values of the noise; and
finally, achieving and maintaining a tolerant range of noise values.
Further scope of applicability of the invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.